Abrolhos Wildlife

Wildlife Ecotours Abrolhos Islands

The Abrolhos Islands waters are home to charming marine mammals like the Australian sea lion and the bottlenose dolphin. You can watch the sea lions as they play in the waters or bask on coral beaches in the sun. Sampson fish are also common and some have become so friendly you can feed these huge fish by hand. Migrating humpback whales also inhabit Abrolhos Islands waters during their migration from around July to October Lying in the stream of Western Australia's warm, southward-flowing Leeuwin Current, the marine environment surrounding the Abrolhos Islands is a meeting place for tropical and temperate sea life.

The Abrolhos Islands are among Australia's most important sites for breeding seabirds. Schools of pelagic (fish that live in the surface or middle depths of the ocean) baitfish provide a ready source of food for significant colonies of nod dies, shearwaters and terns, which breed and roost in the islands' mangroves, sand dunes and foreshores. Large breeding colonies of seabirds exist on many of the Abrolhos Islands, and depend for their food on schools of pelagic baitfish. More than 90 species of seabird have been identified. Smaller seabirds, in turn, provide food for white breasted sea eagles which occur in unusually large numbers throughout the Abrolhos Islands. The islands also mark the northern-most habitat of the Australian sea lion. Once abundant, the Australian sea lion is now classified as a ‘vulnerable species'.

The islands lay in the stream of the warm, southward-flowing Leeuwin Current, which funnels warm, low-nutrient, tropical water from the Pacific Ocean down past Indonesia and along Western Australia's continental shelf. It carries a cargo of larvae, eggs and juveniles of many species of corals and other marine life far south of their usual range. The current maintains water temperatures throughout the winter at around 20 to 22 ºC, enabling corals and tropical species of fish and invertebrates to thrive in latitudes where they wouldn't normally survive.

Wildlife and vegetation
The Islands are home to an array of protected flora and fauna that have adapted uniquely to the diverse range of island ecosystems. The Abrolhos Islands are among Australia's most important sites for breeding seabirds. These include a subspecies of the lesser noddy that has its only breeding colony in the Abrolhos Islands, which is a protected haven for their young. Around 10 species of land birds are also present at the Abrolhos Islands with the Abrolhos Islands painted button-quail being notable as it is endemic (found nowhere else) to the Abrolhos Islands.

A total of 25 terrestrial species (many of which are endemic to the Abrolhos Islands) of reptiles occur on the islands: 11 species of skink (including the Abrolhos Islands spiny-tailed skink), seven species of geckos, four species of legless lizard, one species of dragon (the Abrolhos Islands dwarf bearded dragon), one species of elapid (front fanged snake), one species of python and the marine green turtle. Two terrestrial mammal species are found on the Abrolhos Islands: the Tammar wallaby occurs on East and West Wallaby and was introduced to North Island; while the bush rat occurs on West and East Wallaby. Many of the above fauna have special status with either State, or Commonwealth recognition. Scientific interest in these species and their habitats is high and research is undertaken into many aspects of the islands' wildlife

There are over 140 species of native flora at the Abrolhos Islands, all are classified as protected. Some of these are recognized as being of a “priority species” that have very high conservation values. Some of the vegetation communities habituating the islands are: coastal and dune heath, Dwarf shrub land, Salt lakes and low saltbush flats, man gals (patches of mangrove forest) and eucalypt mallee. Some of these communities are highly sensitive to disturbance and have slow rates of regeneration. The shrubby Nitra bush is common on many of the islands. It provides shelter to sea lion pups and a nesting platform for some species of seabird.

Seabird breeding islands
Many species of seabirds breed at the Abrolhos Islands throughout the year. Be aware of seasonal bird breeding times and areas, and avoid visiting such sites. Particular care should be taken in sandy areas, lagoons and mangroves, as these are seabird-breeding sites. Avoid walking through these areas. Take particular care on seabird islands at the following sensitive times: late afternoon, early evening and during the hottest part of the day, during wet and/or cold weather, on moonlit nights, and when nests contain eggs and chicks.

Bird watching with care
Allow seabirds to nest and roost undisturbed. Stressed birds desert their nests, leaving eggs and chicks exposed and unprotected.

  • Keep at least 50 meters from seabird colonies and occupied nests, taking care not to touch or crush eggs, chicks and nests. Stop approaching if birds show signs of distress, such as raucous calling or swooping.
  • Keep loud noises, sudden movements and the use of lights at night to a minimum near bird colonies.
    Wildlife - “look, but do not touch”
  • View wildlife from a distance (especially sea lions and seabirds), preferably from a boat. Hand feeding and direct contact with the unique wildlife populations of the Abrolhos Islands can be harmful, and cause distress and changes in behavior.
  • Always leave a clear unobstructed route between sea lions and the water when approaching resting sea lions on land.
  • Leave all wildlife where it is found, including live shells, fossils and corals. Collecting damages the health of the islands' ecosystems and is prohibited without a license.
  • Avoid handling or touching sea creatures as many fish, mollusks, urchins and anemones have venomous spines or stinging nematocysts that can cause symptoms ranging from minor irritation to paralysis and heart failure.
  • Report injured wildlife sightings
  • Be cautious when approaching the animal. Gather information on the severity, location and type of injury.
  • Contact the Department of Environment and Conservation (Geraldton office).

Preserve island habitats

  • No camping, fires, firearms or pets are allowed at the Abrolhos Islands.
  • Take all your rubbish away with you.
  • Keep to existing tracks, and to beaches and rocky shorelines, to avoid damaging vegetation and bird-breeding areas.
  • Check for seeds and spores on shoes before landing to prevent the introduction of exotic plants.

Minimize boat impacts to Marine Habitats

  • Use public moorings where available to avoid the use of anchors and chains, which can damage coral reefs and sea grass beds.
  • When moorings are not available, anchor in areas of sand and mud bottom and avoid reefs and sea grass areas.
  • Know your vessel's draught and your limits in the shallows. Use current charts and navigational aids, where available, to prevent impact and propeller damage to reefs.
  • Keep the waters clean. Silage tanks should be emptied at sea a kilometer or more from land, including islands.
  • Remove and store all hard waste and dispose of it appropriately at your nearest port.

Fish responsibly and “Fish for the future”

  • Take no more fish than for your immediate needs, as fish has a short freezer life. Return unneeded and undersized fish to the water, quickly and with care.
  • Know and keep to recreational fishing seasonal, bag, size and possession limits.
  • Be aware of the boundaries and fishing restrictions that apply within the Reef Observation Areas (see map for locations).
  • Do not feed fish. Observe the fish of the Abrolhos Islands without disturbing their feeding patterns.
  • Dispose of waste from fish cleaning outside anchorage areas. Fish offal dumped off jetties and moored boats encourages yellowtail king fish and Samson fish to feed and can trigger unwanted changes in their behavior.
  • Dive without damage - enjoy the life of the reef
  • Observe the reefs without impact. Do not rest or stand on corals and fragile marine life.
  • Control your buoyancy to prevent contact and damage to corals and marine life.
  • Be aware of your fins to prevent careless kicks from breaking corals and stirring up the sediment.
  • Secure loose dive equipment to prevent it dragging across corals.
  • Leave live shells, reef fish and animals as they are. Learn about the underwater environment so that you can better appreciate it.

Terrestrial flora
The flora of the Abrolhos Islands is generally the same as the coastal flora of the adjacent mainland, with the exception of the islands' mangrove, saltbush and salt lake vegetation.
Flora. The vascular flora of the Abrolhos Islands has been thoroughly surveyed, and species lists have been published for 119 islands. As of 2001, these lists totaled 239 species from 68 families. A further six species have been collected in the Abrolhos Islands, but cannot be allocated to islands because insufficient location information was recorded. There have also been collections of mosses, liverworts and lichens, but no information has been published on these non-vascular groups.

The islands with the greatest floristic diversity are East and West wallaby Islands, with 124 and 97 species respectively. 54 species occur in all three island groups. The most widely distributed species are Nitraria billardierei, which has been recorded on 106 islands; the exotic Mesembryanthemum crystallinum, on 88 islands; (Coast Bonefruit), on 72 islands; and (Grey Saltbush), on 70 islands. On the other hand, (Ooragmandee) and Acacia didyma occur only on East Wallaby Island. As of 2001, 5 species of priority flora occurred on the islands. 95 exotic species from 29 families have been recorded. In general, islands that have or had human settlements are the weediest. Of greatest concern is the noxious weed (African Boxthorn), which has long spines that can trap birds. This weed was recorded on the islands as early as 1970. Efforts to eradicate it began in 1990, there was a lull in eradication in the late 1990s, but the program was later reinstated, and in July 2007, the Department of Environment and Conservation reported that the species had been eradicated from 14 of the 18 islands on which it had been recorded.  Other noxious weeds include Prickly Pear, Paterson's Curse.

The vegetation is mostly chenopod shrubs.

Terrestrial fauna - Birds
The Abrolhos Islands is home to around 100 species of bird; for a complete list, see list of birds of the Abrolhos Islands. Six species are land birds, and three are shore birds. The remainders, the vast majority, are seabirds. Most seabird species have a tropical distribution, but some occur in both tropical and warm-temperate seas, and a small number are warm-temperate only. When numbers of individuals are taken into account, the tropical birds overwhelmingly dominate. The islands are one of the most important breeding sites for tropical seabirds in Australia. They contain by far the largest colonies of Wedge-tailed Shearwater in the eastern Indian Ocean, with over a million breeding pairs recorded there in 1994. They also contain Western Australia's only breeding colonies of the Lesser Noddy, and the largest colonies in Western Australia of the Little Shearwater, White-faced Storm Petrel, Common Noddy, Caspian Tern, Crested Tern, Roseate Tern and Fairy Tern. In addition, they contain important breeding areas for the Eastern Reef Heron, Pacific Gull, Bridled Tern, White-bellied Sea Eagle and Osprey.

There are two subspecies of bird endemic to the islands. The Abrolhos Islands Painted Button-quail occurs only on five islands in the wallaby Group, and is protected as rare under the Wildlife Conservation Act 1950. Also gazette as rare, the Australasian subspecies of the Lesser Noddy, breeds only on Wooded Island, Morley Island and Pelsaert Island.

Only two species of land mammal are indigenous to the Abrolhos Islands, the Tammar Wallaby) and the Bush Rat. Both are native only to West and East Wallaby Islands, although R. fuscipes has not been collected on East Wallaby Island since August 1967, and is probably extinct there. The Tammar Wallaby was seen on West Wallaby Island by survivors of the 1628 Batavia shipwreck, and recorded by Francisco Pelsart in his 1629 Ongeluckige Voyagie. This represents the first recorded sighting of a macropod by Europeans, and probably also the first sighting of an Australian mammal. Tammar Wallabyes were introduced to North Island from East Wallaby Island by fishermen, probably in the 1950s, but failed to establish. In 1987 they were reintroduced again, this time successfully. By the 2000s, there were over 400 Wallabyes on the island, resulting in overgrazing of native vegetation and increased erosion. Research into the effectiveness of controlling population levels by the use of implanted contraceptives was begun in 2005, but in July 2007 the research was discontinued and the population culled instead.

Two introduced mammals are established on the islands. The Domestic Cat was introduced to Rat Island around 1900, and the House Mouse was introduced onto North Island in the 1970s, presumably with food. In 1995 the House Mouse was reported as also present on Rat Island for many years before 1987, but a recent report makes no mention of this. In addition, three introduced mammals were previously established in the Abrolhos Islands, but have since been eradicated. The Black Rat was established on Pigeon and Rat Islands, but has been eradicated by poisoning. The European Rabbit has been introduced at various times onto Leo Island, Middle Island, Morley Island, Pelsaert Island and Wooded Island. In the case of Pelsaert Island, it is not clear whether it ever established; in all other cases, established populations have been eradicated by poisoning. The Domestic Goat is also reported to have been present on East Wallaby Island, but is no longer.

23 terrestrial reptile species are known to occur on the islands of the Abrolhos Islands. This relatively low biodiversity is apparently due to the homogeneity of habitat on the islands, which provide few distinct ecological niches. The most significant terrestrial reptile species are the Spiny-tailed Skink and the Carpet, both of which are listed as rare and therefore afforded special protection under the Wildlife Conservation Act 1950; and the Abrolhos Islands Dwarf Bearded Dragon, a Abrolhos Islands endemic that is listed as a Priority 4 species by the Department of Environment and Conservation.

Specimens of the Pobblebonk and the Turtle Frog were collected from the Abrolhos Islands during the Percy Sladen Trust Expedition of 1913 and 1915, but no amphibians have been recorded on the islands since that time. 260 species of benthic algae have been recorded at the Abrolhos Islands. This figure comprises 178 species of red algae 50 species of brown algae and 32 species of green algae both temperate and tropical species are present, in many cases near the northern or southern extent of their range.

Sea grass
Only ten species of sea grass have been recorded at the Abrolhos Islands. Seven of these are temperate species at or near the northern limit of their range; the other three have a tropical distribution. That there are so few tropical species may be due to periods of low sea temperatures, or the small areas of suitable habitat at the Abrolhos Islands; alternatively it may be that more collecting effort is needed in habitats that suit tropical species. At last count, a total of 389 species of fish have been recorded from the Abrolhos Islands. 16 species occur in very large numbers; in decreasing order of abundance.

Marine mammals
The Abrolhos Islands maintains a breeding population of Australian Sea Lions probably numbering between 75 and 100. Historical data suggests numbers were previously much higher for example, in 1727 survivors of the Zeewyk shipwreck killed over 150 sea lions in the Southern Group alone. This has led to a 1727 population estimate of between 290 and 580 animals for the entire Abrolhos Islands. Populations apparently fell dramatically between the 1840s and the 1880s, largely due to extensive commercial sealing in the area. In addition to direct killing of the animals, it is likely that much of the mangrove habitat on the islands was cleared as fuel for trypots, and this may have affected the survival of young pups. Populations are thought to have been fairly stable for the last fifty years, although the lack of genetic diversity in the smaller population remains of concern, as does climate change.

Sea lions come ashore to rest on leeward beaches throughout the island chain, but only a small number of these "haul out sites" are used for breeding. Breeding has been observed on Serventy Island, Gilbert Island, Alexander Island, Suomi Island, Keru Island, Square Island, Stick Island, Gibson Island, Gun Island, Morley Island and Wooded Island. All but the last three of these are considered current breeding sites, and are therefore considered by the Department of Fisheries to have a high conservation value.

Little information is available on other marine mammals at the Abrolhos Islands, as no direct research on this subject has been undertaken. Sightings of the Humpback Whale are common between April and October, when the whales are migrating. Other marine mammals sometimes sighted at the islands include Pygmy Bryde's Whale, Bottlenose Dolphin and Striped Dolphin.
Marine reptiles

The Green Turtle and the Loggerhead Turtle both live in the waters off the Abrolhos Islands, albeit in low numbers. Neither species breeds in the area, as water temperatures are too low. The Abrolhos Islands is unusual in having a luxuriant and diverse living coral reef at such high latitude. 194 species in 50 genera have been recorded there, all but two of which are tropical. This is a surprisingly high coral diversity, considering the high latitude of the reef, and the relatively low diversity of other biota. The coral reef community at the Abrolhos Islands is unusual in having tropical coral growing alongside and in direct competition with, temperate seaweed. As a result of this competition for light, space and nutrients, coral at the Abrolhos Islands tends to grow more slowly and die younger than is usual. Reef production is to a large extent due to the production of carbon by coralline algae rather than by coral.

The most notable species of crustacean at the Abrolhos Islands is the Western Rock Lobster 44 species of crab and 9 species of amphipod were recorded there by the Percy Sladen Trust Expedition of 1916.
Mollusks. 492 species of marine mollusk have been recorded from the shallow waters of the Abrolhos Islands. These are predominantly gastropods (346 species, 70%) and bivalves (124, 25%); the remaining 5% of species consist of cephalopods (14 species), chitons (5 species) and scaphopods (3 species). About two thirds of the species have a tropical distribution, temperate species account for 20%, and the remaining 11% are endemic to Western Australia. The Southern Saucer Scallop is the only commercially important species. This occurs in sheltered areas of medium-fine sand in deep water to the north-east of the reefs; it is usually the dominant species there.

Abrolhos Islands has an extremely high diversity of echinoderms, with 172 species having been recorded there. 63% of these are tropical species, 14% are temperate, and 22% are endemic to Western Australia. None is endemic to the Abrolhos Islands. Published surveys have not included observations of the crown-of-thorns starfish but individuals have occasionally been observed there.

Other invertebrates
The sponges of the Abrolhos Islands are poorly studied, although 109 species of demo sponge have been collected there. In the most recent survey, 77 species were collected, of which around half are probably new to science. Only two locations were surveyed in this study, however, so this figure is likely to represent only a small proportion of the total sponge fauna of the Abrolhos Islands; the islands are therefore thought to harbor an extremely rich diversity of sponges. A preliminary assessment suggested that there were more temperate species than tropical, which stands in marked contrast to most other groups.


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